请问“在读医学博士”怎么用英语表达的？

I am studying for MD degree with Prof. Li as my tutor(导师) right now.——略换角度，本意未变
I study as a MD candidate guided/tutored(2选1) by Prof. Li.
I am a MD postgraduate directed by Prof. Li.
印象中，postgraduate似较candidate常见些，毕竟后者还可译为准（博士），即已考取博士、但还未入学者，可能引起歧义
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Reading a medical doctor

Ph.D candidate of Medecine